The fortress of Dongning, also known as the "fortress of the Japanese invasion of China by the Dongning Army", is the largest military fortress in Asia and the last battlefield of the Second World War, known as the "East Maginot Line". Dongning Fortress, located in Dongning County of Mudanjiang River, is a military fortress built by Japanese invaders to defend against the attack of the former Soviet Union. It begins in the north at the North Yan King's Hall of Suiyang Town and reaches Ganhezi in the south. Its front is more than 100 kilometers wide and its depth is more than 50 kilometers.